prelude (noun) - an action or event serving as an introduction to something more important.
I was working on the jean wall in my department today, and I had several folded pairs grouped by size laying on the floor, and had gone to use the restroom. Coming back, this guy arrives upon the scattered piles right as I walk up to them. He immediately goes off, and I apologize for the mess. He then laughs, and says, "Oh! You're working on this. Whew! I thought some jerk had just thrown them down on the floor!" He was legit ready to fight whoever had done this to my wall, and it was so cute.